The price of putting someone down via lethal injection is approximately $2 Million per case.
The price of LWOP (Life Without Parole) is $1.2-3.6 Million more than lethal injection, after all trials.
Utilizing the death penalty will also be sure to stop prison overcrowding and if a murderer is killed, they can't cause anymore trouble, in jail, or if they were to escape.
Although the death penalty will cost more up front, in the end, life sentencing is more expensive.
Because of overcrowded prisons, the government is forced to build more, costing even more money.
Actual Quote from George W. Bush